1. Field
This disclosure generally relates to the field of iontophoresis and, more particularly, to the delivery of active agents such as therapeutic agents or drugs to a biological interface under the influence of electromotive force and/or current.
2. Description of the Related Art
Iontophoresis employs an electromotive force and/or current to transfer an active agent such as an ionic drug or other therapeutic agent to a biological interface, for example skin or mucus membrane.
Iontophoresis devices typically include an active electrode assembly and a counter electrode assembly, each coupled to opposite poles or terminals of a voltage source, for example a chemical battery or an external power station connect to the iontophoresis devices via electrical leads. Each electrode assembly typically includes a respective electrode element to apply an electromotive force and/or current. Such electrode elements often comprise a sacrificial element or compound, for example silver or silver chloride.
The active agent may be either cationic or anionic, and the voltage source can be configured to apply the appropriate voltage polarity based on the polarity of the active agent. Iontophoresis may be advantageously used to enhance or control the delivery rate of the active agent. The active agent may be stored in a reservoir such as a cavity. Alternatively, the active agent may be stored in a reservoir such as a porous structure or a gel.
An ion selective membrane may be positioned to serve as a polarity selective barrier between the active agent reservoir and the biological interface. The membrane, typically substantially only permeable with respect to one particular type of ions (e.g., a charged active agent), prevents the back flux of the oppositely charged ions from the skin or mucous membrane. Although combining membranes in layers with iontophoresis results in efficient, controlled delivery of the active agents and allows for flexibility in choosing the electrode system, delivery from these membranes may be difficult. Because the biologically active agent, such as a drug or vaccine, may have to be deposited on the membrane in dry form, the amount of drug absorbed thereon may not be sufficient to meet the dosage requirement.
Commercial acceptance of iontophoresis devices is dependent on a variety of factors, such as cost to manufacture, shelf life, stability during storage, efficiency and/or timeliness of active agent delivery, biological capability, and/or disposal issues. Commercial acceptance of iontophoresis devices is also dependent on their ease-of-use and versatility, as well as their ability to provide effective and controlled delivery of biologically active agents. Therefore, it may be desirable to have novel approaches for providing controlled delivery of active agents using iontophoresis devices.
The present disclosure is directed to overcome one or more of the shortcomings set forth above, and provide further related advantages.